Lesson 4: Adjusting Muscle Length
 
 
 

A muscle created using the Muscle Creator has three built-in cross section curve sets that you can edit: one for the default rest position, one for the squash state, and another for the stretch state. You can directly edit these curves in the scene view, or using the Muscle Creator window. The following example shows you how to adjust the muscle for each of its poses.

Load the scene

  1. Load the Sabertooth_Adjust_Muscle_Length_Start.mb file.

    This scene contains the sabertooth tiger with capsulated bones, a front leg muscle, and a neck muscle that has been set in all three pose states.

  2. Scrub the timeline frame by frame to see the neck muscle squash and stretch.

    Notice that the neck muscle travels down from the cervical joints to the humerus joint in a straight line, which causes the muscle surface to either stick out too much from the tiger’s body, or go through the shoulder joints. This not only looks bad, but also affects how the muscle works. To fix this, we’ll change the muscle’s center line for each of its pose states so it follows the contours of the tiger’s body.

  3. Select Muscle > Muscles/Bones > Muscle Creator from the main menu.

    The Muscle Creator window opens.

  4. Go to frame 0 in the Time Slider, which is the rest state set for the neck muscle.

    Select the neck muscle surface if it isn’t already.

  5. Click the Edit tab in the Muscle Creator.
  6. In the Attach Rest section, select AttachMidMus_L_Neck11.

    This selects the first inner wireframe box at the top of the neck muscle, which represents the attach point for the nearby cross section.

  7. Using the Move tool, begin reshaping the top part of the neck muscle so it goes around the cervical joint instead of going through it.

  8. Repeat the process with the remaining attach points until you’re satisfied with the results. The muscle shape should be organic and follow the tiger’s body.

    Do not worry about adjusting these attach points too perfectly, as you can come back later to tweak them some more.

  9. Go to frame 5 in the Time Slider, which is the squash state set for the neck muscle.
  10. Adjust the center line for this state by first selecting the attach point from the Attach Squash section of the Edit tab, and then reposition them using the Move tool.

  11. Go to frame 17 in the Time Slider, which is the stretch state set for the neck muscle.

    Here you will notice that the muscle needs correction.

  12. Select the attach points from the Attach Stretch section of the Edit tab, and then reposition them using the Move tool so that the muscle goes around the shoulder before ending at the humerus.
  13. Scrub through the animation to view the changes you have made.

Beyond the Lesson

In this lesson you have learned how to adjust the muscle’s length by altering its center line. A completed file for this lesson, Sabertooth_Adjust_Muscle_Length_End.mb. Now you are ready to sculpt the muscle surface.